Typical applications of frequency converters are electric motors and devices for producing renewable energy over a wide output power range and voltage range (generally below 1 kW . . . over 1 MW and 230 VAC . . . 690 VAC). For covering these requirements it is necessary to design and manufacture a number of devices intended for different output powers because one single device construction is not technically or economically a reasonable option.
It is not, however, economically reasonable to optimize a device construction dedicated to each motor output power of each voltage range, but instead a typical method is to design and manufacture a plurality of device constructions (frames), each of which covers its own specific performance range. The performance values are generally indicated at least as a rated current value and as a voltage class.
It is economically advantageous to set a sales price for each output power and voltage separately, because e.g. frequency converters have a number of applications for which the price obtained from sold devices is determined according to both the market area and the product properties. This results in the current values and voltage values implemented by one frame being productized for the market as different and parallel product names. Productization typically takes place by varying the current values and/or voltage values possible for the frame either by adapting the physical structure of the product and/or with software-based adjustments, as well as by enabling or preventing the use of various optional extras.
Since current values and voltage values belong to the description of the essential information about an electrical device, these values must be recorded on the nameplate of a product in accordance with the requirements of international safety standards, such as e.g. IEC 60204-1 and IEC 61439-1. The nameplate must be affixed to the device in a reliable manner and the plate must remain legible in the operating conditions defined for the device.
Use of the same device construction for manufacturing a number of different products delivers economic advantages in the production phase of subassemblies, because there are fewer structures to be produced and structure-specific volumes are therefore larger. The advantages achieved in manufacture diminish, however, in final assembly, outfitting, distribution and servicing activities, because the current values and voltage values according to the sales range, as well as possible product variants, increase the number of items to be maintained and stored, which in turn results in the product distribution stage in the value of inventories tending to rise and inventory turnover tending to fall.
Efforts have been made to solve the problem e.g. with various software keys, the distribution and sales of which is, however, difficult owing to sales chains comprising numerous different agents. In addition, variation of current values and voltage values is not, however, possible merely with software because the nameplate must correspond to the configuration of the device.